Slide-out rooms extend and retract from the main body of recreational vehicles (RVs) and other types of manufactured housing to provide additional living space. While a popular and convenient feature, the mechanisms used to move the slide-out room between its extended and retracted positions have heretofore suffered from a variety of operational and manufacturing problems. An array of hydraulic, pneumatic and electro-mechanical actuation devices (“actuators”) have been employed with varying degrees of success, including screw drives, chains, rack and pinions, telescoping rams, as well as various linkage arrangements. Typically, these actuation mechanisms have been disposed under the slide-out room floor or within the slide-out room sidewalls. Conventional actuation mechanisms often needed support arms and other linkage members to support and guide the slide-out room as it moves between the extended and retracted positions. As such, the actuation mechanisms and support members occupy space within the slide-out room and main compartment which is lost as living space. In addition, the installation of these actuation mechanism in the manufacture of slide-out room structures is often difficult. Because the slide-out rooms and compartment openings are seldom perfectly square, the installation and alignment of the actuation mechanism often requires extensive adjustments and reworks. Misalignment of the actuation mechanisms can cause the mechanical components to wear and their operation to fail over time. Servicing and repairing the actuation mechanisms is also complicated by the lack of access to the mechanisms, which are embedded within the floor and walls of the slide-out room and compartment. Consequently, it is always desirable to minimize the size, weight and cost of the actuation mechanism, as well as to improve the ease of its manufacture and service.
The present invention provides an improved actuation mechanism (“actuator”) for slide-out room applications. The actuator uses timing belts as flexible rack members in a rack and pinion type drive mechanism. Timing belts have been used in a variety of other applications, but heretofore not as part of a rack and pinion drive mechanism. The timing belts are mounted to the slide-out room and drive blocks are mounted at the top and bottom of the slide-out opening of the main compartment. A pair of timing belts are mounted at the corners of the slide-out room top and floor, each running longitudinally to the direction of the slide-out movement. Each drive block includes a pinion and two idle rollers. Each timing belt passes through a drive block being trained around the pinion between two idle rollers in a serpentine fashion. A reversible electric motor, which is operatively connected to all four pinion blocks, simultaneously turns the pinions to propel the timing belts through the pinion blocks thereby extending and retracting the slide-out room through the slide-out opening. The ends of the timing belts are secured to the slide-out room using U-shaped channel and clamping plates, which allow for longitudinal adjustment of the belt position.
The actuation mechanism embodying the present invention provides several significant benefits over conventional slide-out actuating mechanisms. The use of flexible timing belts greatly reduces the height and profile of the actuation mechanism thereby increasing the useful living space of the slide-out room, as well as reducing the weight of the mechanism itself. Using four timing belts eliminates the need for additional support members, which also helps maximize living space. The polyurethane timing belts are light weight, durable and generally maintenance free. The reduced weight of the timing belts over traditional rigid metal racks means smaller and less costly drive motors and components can be used.
The use of timing belts in the actuator of this invention also provides manufacturing and maintenance advantages in slide-out room applications. Because timing belts are durable, resist stretch and require little lubrication, the actuator of this invention requires little care or maintenance once installed. In the rare case that adjustment or replacements are needed, the majority of the actuator's components are readily accessible. The timing belts are easily mounted to the slide-out floor and top, which means improved manufacturing ease. The mounting channels and clamping plates allow the slack timing belts to be quickly and readily tightened once operatively mated through the drive block. More importantly, the mounting channels and clamping plates allow for the adjustment of the timing belts relative to the slide-out room so that the slide-out room can be retracted and extended squarely from the main compartment.
These and other advantages of the present invention will become apparent from the following description of an embodiment of the invention with reference to the accompanying drawings.